Airway Management In the Patient In Shock

The key functions in emergency and critical care management of the shock patient are appropriate airway management and hemodynamic support.

[6-24-2017 Rapid sequence intubation can precipitate hypotension. Be sure to have your pulse dose pressor prepared and ready to go for any intubation as you never know. To view Dr. Weingart’s pdf click on mixing instructions for epinephrine and phenylephrine. To find more resources on push dose/pulse dose pressors type in “pulse dose pressors” into the search box.]

Patients in shock, both compensated and uncompensated, may require endotracheal intubation and ventilatory support.

However, these procedures are often associated with pre- or postintubation hypotension which is a serious problem. “Post-intubation hypotension (PIH) occurs in one quarter of normotensive patients undergoing emergency intubation and is severe (SBP < 70 mm Hg) in up to 10% of cases.” (1)

“Preintubation shock increases the likelihood of severe complications, including cardiac arrest, during or following intubation. Intubation and mechanical ventilation can have substantial negative impact on fragile cardiovascular status. Medications and positive pressure ventilation may reduce cardiovascular performance and precipitate irreversible decompensation. Cardiac arrest rates as high as 15% are described during airway management of patients in hypotensive shock. If the patient is adequately oxygenated [meaning you aren’t “forced to act”] fluid and catecholamine support is advised before initiating the intubation sequence.” (2).

Preoxygenation (3)

For patients in shock, bag mask ventilation may be needed between induction and intubation if the oxygen saturation falls below 90% or if there is severe acidemia (pH < 7.1).

In critically ill patients monitoring oxygen saturation with the forehead reflectance probe is preferred over the finger probe because it is more reliable during hypotension. “Limited detection of cutaneous arterial pulsatility generally reduces accuracy of pulse oximetry with SBP < 80 mm Hg.”

Rapid Sequence Induction (RSI) (4)

“Pretreatment opioids are contraindicated in patients with comrpomised cardiovascular status including compensated shock.”

The agents indicated for RSI in uncompensated shock (hypotension) and in compensated shock are etomide and ketamine. “. . . both etomidate and ketamine require dose adjustments for adminstration to shocked patients (e.g., etomidate 0.1 to 0.15 mg per kg or ketamine 0.5 to 0.75 mg per kg). It is better to err on the side of too little rather than too much. Airway managers should anticipate delay in drug onset resulting from dose adjustment and the prolonged circulation time. Neuromuscular blocking agents pose little hemodynamic risk and should be dosed normally.”

Remember, that at the first thought that you might need to do an awake intubation, you need to give glycopyrrolate 0.01 mg IV (usual adult dose, 0.4 to 0.8 mg IV) for mucosal drying. It takes ten minutes to work and twenty minutes is better according to the Airway Manual.

“Progressive bradycardia not associated with hypoxia or laryngoscopy is a frequent sign of terminal shock and impending cardiac arrest.”

Postintubation Management (5)

Positive pressure ventilation (PPV) limits venous return in hypovolemic patients. And auto-PEEP from retained intra-thoracic volume can develop from positive pressure ventilation and, if not recognized, can lead to irreversible hypotension and cardiac arrest.

The key to limiting the negative effects of PPV is to use a slow respiratory rate and low tidal volume (10 to 12 breaths per minute and a tidal volume of 7 ml per kg).

“Vasopressor support should be immediately available to reverse life-threatening hypotension. Preintubation hypotension is more easily managed with catecholamine infusion initiated before intubation.”

The Intubation Bundle for Patients With Shock (6)

A multi-center study of an “intubation bundle”, a set of procedures, in patient being intubated in the ICU showed a reduction in severe hypoxia and hypotension.

It is very important to recognize that this protocol is not completely appropriate for ED shock patients.
The etomidate or ketamine dose used for induction in this protocol are inappropriate and are much higher than the doses recommended in the Airway Manual cited above. Also the Airway Manual as noted above recommends catecholamine infusion be begun before intubation in hypotensive patients. “Preintubation hypotension is more easily managed with with catecholamine infusion initiated before intubation.” (5)